The issue seems straightforward. If you reach 300 C, auto-catalytic reactions will lead to temperature rise and the material will become char with significant evolution of tar. Depending on the biomass, you should raise the temperature to about 220 to 250 C and not more than that for torrefaction. If you fill the biomass in a container with little void fraction (some unavoidable void is no issue) and heat up, the initial generation of bound moisture, between 100 to 150 C will itself drive away all the oxygen. The issue in operation is not the presence of oxygen, but the heating rates you can get from solar system. I guess you must have a solar concentrator. Designing that system will be a more important issue to be addressed. Good luck on that and no worries on oxygen, as far as I can see.

if the overall application is heated to 250 deg C, will the oxygen be burn already?

The best way to remove oxygen is for the container to be connected with a vacuum pump. The container had better to have a valve to switch ON/OFF.

Hope it helps.

Qoriatul Fitriyah But it causes the biomass to burn as well right? I just want to remove Oxygen before the biomass get burned and damaged.

yes it is. is it possible to make the temperature low enough before you start to burn the biomass up to 300 deg C? If so, then 'wet activated carbon' maybe interesting enough for you

Hi Danuja,

I'm not familiar with your process, but for other applications I removed oxygen using two alternative methods:

a) by displacing it from the chamber with Argon or other non-reactive gas

b) using a vacuum pump

Hope this helps.

Hi Danuja,

Adding all the above suggestions, you could use a nitrogen filled plastic bag to process your materials. This is the cheapest solution. Please see the picture attached. If you could find a glove box system in some where, that could be ideal.

Hope it helps

Xuhua

There are two sources of Oxygen in a biomass filled container. The first one that you can get rid off is the oxygen in air. A vacuum pump with proper inlet filtre and gauge you can evacuate to a certain level. For more effective I usually send some Nitrogen for a couple of tens of minutes to the container. But if you want to be more precise in evacuating oxygen than I use helium with some pressure and repeat it with a vacuum pump at least 3 times. The other source is the oxygen which is inside moleculer structure of biomass so you make the torrefaction for this. But due to torrefaction conditions the oxygen in molecular structure will come out as CO2, CO or higher hydrocarbons. The reactions are mostly exo and you can see the difference between the source and container temperature.

The issue seems straightforward. If you reach 300 C, auto-catalytic reactions will lead to temperature rise and the material will become char with significant evolution of tar. Depending on the biomass, you should raise the temperature to about 220 to 250 C and not more than that for torrefaction. If you fill the biomass in a container with little void fraction (some unavoidable void is no issue) and heat up, the initial generation of bound moisture, between 100 to 150 C will itself drive away all the oxygen. The issue in operation is not the presence of oxygen, but the heating rates you can get from solar system. I guess you must have a solar concentrator. Designing that system will be a more important issue to be addressed. Good luck on that and no worries on oxygen, as far as I can see.

Hanasoge Mukunda I get your point. But how can I make sure that all the biomass gets the similar amount of heat or having a high mass yield of torrefied biomass without leaving a bulk of un-torrefied biomass by filling the reactor with biomass ? Then I have to use a rotating bed reactor i guess to provide a better mixing.

The answer to your question is simple. The thickness of the fuel filled zone must be segmented so that heat penetrates all parts. You can do this effectively in larger reactors. Otherwise send heated steam (at 200 or 250 C) through the system. There may be other methods as well. But this question is different from the one you sought to get an answer in the first place!

Reactor design is an issue that should be addressed at some depth. Then the solution may be obtained.

Hanasoge Mukunda That question was a sub question that came into my mind with your answer. I think reactor designing is the crucial part here which will effectively transfers the heat to the Biomass. We have already looked into the solar concentrator design as well. Thank you Sir. Appreciate your helpfulness.

Thank you everyone who contributed to the discussion as well !

Dear Danuja Samaranayake ,

This is an interesting idea. My take is that you can simply flush the entire reactor or reaction chamber with nitrogen or argon before connecting it to the solar part of your experimental set up. If that's not possible, then your can stack the reactor (i.e.) fill it up completely with the fuel feedstock (depending on particle size) without any spaces whatsoever. I have tried this approach for pellets and cube sized fuels for torrefaction and pyrolysis on a muffle furnace reactor without the need for flushing with an inert gas. The mass yield obtained we between 70-76% for charcoal (pyrolysis) and 55-95% for torrefaction. Hope this helps.

What is the volume of Your container? The best method is highly dependent of which volume must be filled with an inert gas.

Is it a batch reactor or continually fed reactor?

Henrik Romar This is actually a lab scale experiment. So volume won't be very much and we haven't still designed the reactor. But FYI we are experimenting this to scale up firstly to a pilot scale and finally to the industrial level where high volumes are used.

Humberto Santos Its a batch reactor.

In that case, fill the reactor with wood, flush it with nitrogen. The process will create cases to keep it oxygen free. But keep a slow flow of nitrogen in order not to create a pressure and to remove the gases. You need an inlet connector for the nitrogen and an outlet connector for the cases.

Take a metalpipe big enough, weld collars at both ends and bolt lids at both ends. Make holes and connect the inlet and outlet connectors.

Henrik Romar Thank you for the valuable ideas !

Dear researchers,

Have a nice weekend with your family....